1. Field of the Invention
The present invention relates to mobile telephone networks, and in particular to the processing of calls or other subscriber events or sessions in such networks. Such calls, events and sessions may include, for example, the sending and receiving of messages (SMS), General Packet Radio System (GPRS) events, Internet and Intranet sessions, and the provision of multimedia services. Subsequently, the term ‘call’ will be used to refer to any or all of such calls, events or sessions. Call processing is the operation or operations carried out by the network and by services supported within the network in response to initiation of a call by user. Call processing may be considered as involving either or both of call handling and service handling, the former being the operations associated with putting a call into effect on the network, and the latter being the operations associated with the delivery of a service as part of the call.
2. Summary of the Prior Art
Mobile telecommunications networks provide more services than the simple establishment of a communication path from one telephone (mobile or land line) to another telephone (mobile or land landline). For example, services such as voice messages may be provided to subscribers to the network, and the network operator may also provide facilities such as call barring, call forwarding, messaging facilities (SMS), voicemail, WAP, internet access, location based services and content services. A further issue is that mobile telecommunications networks generally have a more complex charging structure than land-based networks, and the facility for pre-payment for calls means that the network must be able to determine if the mobile telephone being used can be permitted to function.
In order to achieve this, a mobile telecommunications network may have a series of call handling and/or service handling platforms, each able to carry out one or more specific functions. The processing of a call may involve a plurality of platforms with parts of the call processing being performed on respective platforms and the call being passed from one platform to another at different stages in the processing of the call. Thus, for example, if a pre-pay subscriber wishes to access a voice message, the operations of assessing whether the subscriber has sufficient credit to use the service, and the provision of the voice message itself, may be carried out on different platforms. It should be noted that a platform is a logical structure, i.e. the hardware/software required to carry out the function or functions provided by that platform may be distributed around the network.
In some current arrangements, each platform must act as a relatively self-contained unit, and thus must have access to information about each user. Thus, in the known arrangements, call processing platforms must have, or have access to, an appropriate database, and must also be capable of understanding all possible instructions (i.e. processing commands from the subscriber or network) that can be used.
This creates three problems. Firstly, it makes each call processing platform complex. Secondly, since different platforms may operate to different protocols, incompatibilities can occur, for example as a call is passed from one platform to the other at different stages in call handling. Thirdly, if the subscriber to a mobile telephone communications network moves (“roams”) to a different network e.g. moves from one country to another, the services provided by the home network may not be provided by the new network, so the subscriber cannot be provided with those facilities as they move (“roam”). This third problem is particularly acute for pre-pay subscribers; their credit status is stored on the home network but a network to which they have roamed will not have access to their credit status, and thus current arrangements do not permit pre-pay users to roam as extensively as other subscribers.